1. Field of the Invention
The present invention relates to protocols in a data network. In particular, the present invention relates to protocols used among network access device and terminals having power saving states.
2. Discussion of the Related Art
Many communication devices provide “normal” or “active” mode and “power-saving” modes of operation. Normal or active mode typically refers to the device's highest performance mode of operation, in which also is typically the mode with the highest power consumption. A power-saving mode, by contrast, is a mode of operation in which performance is traded off for a lower level of power consumption. Multiple modes of operations with different levels of performance and power consumption are found in most computers and communication devices today. For example, battery-powered devices in wireless communication systems, such as IEEE 802.11 WLAN (Wireless Local Area Network), IEEE 802.16 Wireless MAN (Metropolitan Area Network), GSM, IS-95, W-CDMA, CDMA 2000, all provide active and power-saving modes of operation. In particular, an IEEE 802.11 device has two power modes: an active (i.e., normal operation) and a power-saving mode. Under a power-saving mode, the device shuts off a part of its circuitry. Similarly, an IEEE 802.16 device has three power modes (“normal,” “sleep,” and “idle” modes), each mode having a prescribed level of communication and power-saving capabilities.
Under most conventional power-saving modes, a wireless terminal can be alerted (or paged). Typically, an alerted wireless terminal returns to an active mode of operation to process the packets which have arrived since the terminal entered the power-saving mode.
Some conventional power-saving modes trade-off power consumption and communication capabilities. However, in a conventional power-saving mode, a wireless terminal does not control whether or not packets arriving during a power-saving mode are to be delivered or discarded. For example, under the IEEE 802.11 standard, packets are buffered for later delivery. Under the latest IEEE 802.16 standard at the earliest priority date of this application, however, the packets are either discarded or delivered according to system settings. In addition, a conventional power-saving mode provides a wireless terminal little control over the alert mechanism. Generally, when a packet arrives at a time when the wireless terminal is in a power-saving mode, the wireless terminal is alerted. Efficiency suffers because a terminal lacks control of both packet disposition and the alert mechanism during a power-saving mode.
In a communication network, at times, some packets are of little interest to a wireless terminal. For example, a “Voice over IP” (VOIP) enabled wireless terminal running under the Windows CE operating system may discard all broadcast AppleTalk or IPX packets received. The same wireless terminal, however, may receive NetBIOS packets for file and printer sharing and Session Initiation Protocol (SIP) packets for initiating a VoIP session. Because the wireless terminal does not control packet disposition upstream, even packets of no interest are delivered. However, if the rule is for discarding all packets arriving during a power-saving mode, the performance of a desired service might deteriorate significantly, as its packets are also discarded.
Further, because the terminal lacks control over the alert mechanism, the terminal is alerted by any packet that arrives during a power-saving mode. Clearly, such an alert policy wastes power on undesired packets. In a real computer and communication network, different packet handling methods are required under different power-saving operations. For example, in a VoIP enabled wireless terminal running the Windows CE operating system, while both NetBIOS and SIP packets are relevant in one power mode (e.g. sleep mode in IEEE 802.16), only SIP packets are received in another power mode (e.g. idle mode in IEEE 802.16) to further conserve power.
In some applications, “classification” may be used to determine disposition of a packet. For example, packets may be classified according to source and destination addresses, port numbers and a protocol identifier. In some applications, disposition of a packet may be a decision based on both the identity of the wireless terminal (e.g., its MAC or IP address) and the port number. One example of such an application is a network firewall providing packet blocking services for a security purpose (e.g., to prevent unauthorized access). FIG. 1 is a block diagram showing conventional network firewall 100, including packet classifier 101 under direction of a filter table in filter manager 103. Packets classified to be acceptable are passed to their specific recipients, and packets deemed unacceptable are passed to dropper 102 to discard. Table 1 is an example of a filter table suitable for use in network firewall 100. In network firewall 100, packets are processed without regard to the recipients' power modes.
TABLE 1Network Firewall Filter Table (Prior Art)ClassifierSRCDSTSRC ADDRDST ADDRPortPostProtocolLifetimeActionAny82.48.42.112Any21TCP0DenyAny82.48.42.11280AnyTCP1Allow82.48.42.112Any137137UDPDefaultDeny
In a communication system, “quality of Service” (QoS) capability (e.g., IEEE 802.16) is typically provided to each connection according to a QoS table based on packet classification. Table 2 is an example of a QoS table. FIG. 2 is a block diagram of conventional QoS enabled communication system 200, which includes classifier 201 and QoS mechanism 202. In QoS enabled communication system 200, multiple connections are maintained by connection manager 203. In this example, packets may be classified according to source and destination addresses, source and destination ports, protocol and connection identity (ID) information. According to their classifications, appropriate QoS actions are taken on the packets based on the QoS table. In communication system 200, a packet is also processed without regard to the recipients' power modes.
TABLE 2Connection-Based QoS Table (Prior Art)ClassifierConnec-SRCDSTPro-tionSRC ADDRDST ADDRPortPorttocolIDAction82.68.42.5682.48.42.112803900TCP1QoS spec 182.68.42.5682.48.42.112Any5004UDP2QoS spec 2Any82.48.42.113139139TCP1QoS spec 3
A packet communication method is desired in which each packet is processed according to the packet's classification and the power mode of its recipient. Further, it is also desired of such a packet communication network to determine whether or not to alert a recipient in a power-saving mode.